Splines have been used for many years to join rotary members, particularly cylindrical rotary members together. Generally, one member has a plurality of evenly spaced elongate spaces or grooves and the other member has a plurality of elongate teeth registrable with the grooves and operative to be slidingly received in the grooves and spline the two members together.
Such is commonly employed to join a shaft and gear or a shaft and a flange together by providing a central cylindrical opening through the gear surrounded by a plurality of evenly spaced grooves extending through the gear parallel to the axis of the opening and providing a plurality of elongate teeth circumferentially spaced about the end of the shaft that are registrable with and can be slidingly received in the grooves in a manner effective to provide the splined connections therebetween.
Although single keyway type connections well known to those skilled in the art may be used to join two members together, splined connections are preferred where high torque is involved for uniform distribution of load over a greater surface area provided by a plurality of splines.
It has been the general practice in designing splined connections between rotary members to provide sufficient clearance between the teeth and grooves to enable the teeth to be slidingly received within the grooves with reasonable ease. The practice of providing such clearance, however, enables one of the members to rotate or wobble slightly relative the other which may lead to chatter and wear and does not, without some additional securement, secure them from moving axially relative each other.
In view of such, some modifications have been undertaken to provide tighter securement in splined connections such as disclosed in U.S. Pat. No. 3,360,961, the disclosure of which is incorporated herein by reference, which provides a taper in the grooves so that the teeth are wedged more and more tightly as they are urged along the grooves but which may become too tightly wedged making them difficult to separate and which may over stress the teeth and the groove walls.
Another example of providing a tighter splined connection is disclosed in U.S. Pat. No. 4,175,404, the disclosure of which is incorporated by reference. In this case, the teeth are provided with an axially extending straight section of enlarged breadth providing zero clearance or interference fit with the groove and which then decreases according to a prescribed curve to a straight section having a narrower breadth providing positive clearance with the groove. One of the disadvantages, however, is that in interference fit over a straight length may again over stress the teeth and the groove walls and make the members difficult to separate once splined together.
U.S. Pat. No. 3,477,250, the disclosure of which is incorporated herein by reference, discloses a method of tightening splined connections whereby certain of the teeth are provided with positive clearance and others are provided with zero clearance with the groove as a means of providing a tighter fit but which would be extremely difficult and costly to manufacture and control. The patent also discloses that splines may advance helically along the members as well as parallel to their rotational axis.
U.S. Pat. No. 4,292,001, the disclosure of which is incorporated by reference, discloses members formed by helical splines that are further secured together by means of pins extending through the splines parallel to the rotational axis of the members which again, is costly and difficult to manufacture.
Still another example of a method by which to enhance securement between splined members is disclosed in U.S. Pat. No. 4,552,544, the disclosure of which is incorporated herein by reference. In this case, a resilient coating material is provided over the end of the teeth having a protuberance that extends radially outwardly to provide an interference fit with the bottom of the groove which, although proportedly advantageous for balancing the rotating members, would be subject to undue wear and would not particularly eliminate chatter and wobble under high torque conditions.